Apparatus for low power write and read operations for resistive memory

Abstract

Described are apparatuses for improving resistive memory energy efficiency. An apparatus performs data-driven write to make use of asymmetric write switch energy between write0 and write1 operations. The apparatus comprises: a resistive memory cell coupled to a bit line and a select line; a first pass-gate coupled to the bit line; a second pass-gate coupled to the select line; and a multiplexer operable by input data, the multiplexer to provide a control signal to the first and second pass-gates or to write drivers according to logic level of the input data. An apparatus comprises circuit for performing read before write operation which avoids unnecessary writes with an initial low power read operation. An apparatus comprises circuit to perform self-controlled write operation which stops the write operation as soon as bit-cell flips. An apparatus comprises circuit for performing self-controlled read operation which stops read operation as soon as data is detected.

We claim: 
     
       1. An apparatus comprising:
 a resistive memory cell coupled to a bit line and a select line; 
 a first pass-gate coupled to the bit line; 
 a second pass-gate coupled to the select line; 
 a first write driver to drive an input data to the first pass-gate, the first write driver having a first drive skew; and 
 a second write driver to drive an inverse of the input data to the second pass-gate, the second write driver having a second drive skew, wherein the first drive skew is different than the second drive skew. 
 
     
     
       2. The apparatus of  claim 1  comprises logic to adjust first and second drive skews of the first and second write drivers. 
     
     
       3. The apparatus of  claim 2 , wherein the logic is to dynamically adjust first and second drive skews of the first and second write drivers according to the input data. 
     
     
       4. The apparatus of  claim 1  further comprises: a multiplexer operable by the input data, wherein the multiplexer is to provide a control signal to the first and second pass-gates according to logic level of the input data. 
     
     
       5. The apparatus of  claim 4 , wherein the multiplexer is to receive at least two inputs of different pulse widths. 
     
     
       6. The apparatus of  claim 4  further comprises logic to adjust pulse widths of the at least two inputs. 
     
     
       7. The apparatus of  claim 6 , wherein the at least two inputs are first and second write enable pulses, wherein the first write enable pulse is to control duration of writing a logical high to the resistive memory, and wherein the second write enable pulse is to control duration of writing a logical low to the resistive memory. 
     
     
       8. The apparatus of  claim 1 , wherein the resistive memory is at least one of: STT-MRAM; ReRAM; PCM; or CBRAM. 
     
     
       9. The apparatus of  claim 1 , wherein the resistive memory is an STT-MRAM bit-cell which comprises:
 a select transistor controllable by a word line; and 
 a magnetic tunnel junction (MTJ) device coupled in series with the select transistor. 
 
     
     
       10. A system comprising:
 a processor; 
 a wireless interface to allow the processor to communicate with another device; 
 a memory coupled to the processor, the memory comprising:
 a resistive memory cell coupled to a bit line and a select line; 
 
 a first pass-gate coupled to the bit line;
 a second pass-gate coupled to the select line; 
 a first write driver to drive an input data to the first pass-gate, the first write driver having a first drive skew; and 
 a second write driver to drive an inverse of the input data to the second pass-gate, the second write driver having a second drive skew, wherein the first drive skew is different than the second drive skew; and 
 
 a display unit to display content processed by the processor. 
 
     
     
       11. The system of  claim 10 , wherein the display unit is a touch screen.